Tray dryers
Practical Action
Technical details
The tea chest batch dryer
This, the smallest dryer in the range, is designed to allow trials to be carried out, the production of
samples to demonstrate to buyers and for basic product costings to be calculated. Due to its low
capacity the tea chest dryer is not intended for commercial production but does allow product
development at very low cost.
Construction:
Dimensions:
Capacity:
Heat source:
Cost:
Capacity:
plywood walls over wood frame
0.5 m3
6 trays
2kW electric fan heater wired with external thermostat so that fan runs
continuously
approx. £75
approx. 1kg/day
The large Practical Action semi-continuous
Construction:
plywood walls over angle iron frame
Dimensions:
cabinet 1.4 x 1.2 x 0.9m
Overall height:
2.2m
Capacity:
15 standard trays, each 0.8m2
Heat source:
kerosene/diesel indirect heater-blower. Max heat output
60kW. Air output 2800m3
Fuel consumption:
0.8 gals/hr at 50oC
Throughput:
360 kg/ 24 hrs for herbs
Labour:
3 workers over 24 hrs
Cost in UK:
cabinet £2000
heater £1500
The small Practical Action semi-continuous
Construction:
plywood wall over wooden frame
Dimensions:
cabinet 1.08 x 0.98 x 0.83m
Overall height:
1.9m
Capacity:
13 trays, useful area per tray 0.53m2
Heat source:
direct gas heater/blower (max output 25kW and
470m3 air/hr
Fuel consumption:
0.5lbs per hour at 50oC
Throughput:
120 kg of herbs per 24 hour cycle
Labour:
3 workers on shift
Cost (in UK)
cabinet £600
heater £300
The Anagi dryer
This semi-continuous dryer was developed by IT-Sri Lanka (now Practical Action South Asia) and is
the only design that uses biomass (rice husk) as a source of heat and does not require electricity.
Tray lifting is by a mechanical car jack under the cabinet. Contamination of the product is avoided
by use of a heat exchanger. As the dryer depends on natural convection of air (rather than fans) its
capacity is lower than the powered dryers. Its capital and running costs are however very low
Construction:
Dimensions:
Throughput:
No of trays:
Fuel:
Fuel consumption:
Cost:
timber walls over angle iron frame
4ft x 2ft 8” x 7ft
70-80 kg cashew nuts/day
6
saw dust or rice husk
30 kg/day
£260 in Sri Lanka
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